Depth of Invasion as a Predictor of Contralateral Nodal Metastasis in Lateralized Oral Tongue Squamous Cell Carcinomas

BACKGROUND: This study evaluates the impact of depth of invasion (DOI) on risk of contralateral neck nodal disease (CND) in lateralized oral tongue squamous cell carcinoma (SCC). METHODS: Retrospective review was conducted using a tertiary care institutional database from 1998 to 2021. Patients with lateralized oral tongue SCC who underwent surgical resection were included and evaluated for CND in both primary and recurrent settings. RESULTS: A total of 103 patients underwent 104 surgical procedures. Recurrence was observed in 30 patients (28.8%), and CND occurred in 20 patients (19.2%). Multivariate analysis identified a DOI threshold of 9 mm as the earliest point of statistical significance. Patients with DOI ≥ 9 mm demonstrated approximately 6.5-fold higher adjusted odds of contralateral nodal disease (95% CI 1.5-27.4, p-value = 0.011). CONCLUSION: In this institutional cohort, increasing DOI was significantly associated with a higher risk of contralateral nodal disease.